Electrode for electric-arc lamps



(No Model.)

A. G. SEIBOLD. ELECTRODE FOR ELECTRIC. ARC LAMPS.

No. 447,702. Patented Mar. 3, 1891.

% M5507? QAZZ'ZOM- ALBERT G. SETBOLD, OF MOUNT VERNON, NElV YORK.

ELECTRQDE FOR ELECTRIC-ARC LAMPS.

SPECIFICATION forming part of Letters Patent No. 447,702, dated March 3, 1891.

Application filed October 30, 1890. Serial No. 369,814. (No model.)

To all whom it may concern:

Be it known that I, ALBERT G. SEIBoLD, a citizen of the United States, residing at Mount Vernon, in the county of \Vestchester and State of New York, have invented new and useful Improvements in Negative Electrodes for Are Lamps, of which the following is a specification.

My invention relates to certain improvements in the construction of arc lamps, the purpose thereof being to provide a negative electrode which shall be practically inclestruotible, thereby effecting a very material economy in the carbons now used in ordinary arc' lamps.

It is my purpose to provideanegative electrode capable of being used in any are lamp without regard to the particular construction of the lamp or the system or circuit upon which the lamp is operated, said negative electrode being composed in part of a body of metal of low resistance and in part of a body or shell of carbon deposited upon said metal and covered by a thin sheet of metal electrically deposited thereon, whereby the air is wholly excluded from contact with the said carbon, which is kept cool by the body of metal sustaining the same, thus rendering its combustion and destruction practically impossible, reducing the expense involved in the daily renewal of the carbons, and enabling the trimmers to attend to a given number of lamps in about one half the time usually employed.

The invention consists, to these ends, in the several novel features of construction and new combinations of parts hereinafter fully set forth, and then definitely pointed out in the claims which follow this specification.

To enable others skilled in the art to understand and practice my said invention, I will proceed to describe the same in detail, reference being had to the accompanying drawings, in which- Figure 1 is a sectional view illustrating my invention, the negative electrode being shown in its completed form ready to go into the lamp. Fig. 2 is an elevation showing the electrodes arranged in the lamp, the latter being in operation. Fig. 3 is a central longitudinal section of Fig. 2.

In the said drawings, the reference-numeral 1 denotes the positive electrode, consisting of a carbon pencil of the usual form and adapted to be held in the carbon-holder and fed by the mechanism ordinarily used in arclamps. As these devices are well known, and as they form no part of my present invention, they are neither shown nor'dcscribed in this application.

The numeral 2; denotes the negative electrode, which consists of a rod or bar of metal having a size relatively to the positive electrode substantially as shown in the drawings and being preferably of the shape illustrated, although I do not limit myself to any particular form. About one inchin length of the end of the bar 2 is coated by any suitable means with a layer of carbon 3, having a thickness of about one thirty-second of an inch. This coated extremity is then-introduced within an electroplating bath of copper, a very thin coating 4 of said metal being thereby deposited upon the carbon layer 3, thereby completing the negative electrode in the form shown in Fig. 1. \Vhen placed in the lamp in position for use, the point of the positive electrode 1 rests upon the end of the negative electrode; but when the current is switched on the feed mechanism of the lamp raises the carbon 1 a little distance above the end of the negative electrode and the arc is formed. Upon the formation of the are a circularopening5,having a diameter of about one-eighth of an inch, is burned through the coating of copper on the end of the carbon and copper-coated electrode 2, and as soon as this occurs the arc makes contact with the layer of carbon, the exposed portion of which is coated with acrust 6, consistin g of small particles of carbon deposited from the point of the positive electrode 1 by the action of the electric current. As long as the current is maintained the deposition of these carbon particles continues, and at the same time their consumption gradually goes on, the crust 6 being constantly consumed and constantly renewed.

By constructing the negative electrode in the manner set forth the metallic rod or barf) forms a conductor for the electric current, while the layer of carbon 3 acts as a carbon electrode when the electric arcis formed. The coating of copper 4 excludes air from the carbon layer to effectually prevent its combustion should it become heated to rednofs by the heat of the are. This result, however, is exceeding improbable, since the resistance of the rod or bar 2 being low heating is not only very unlikely to occur, but the bar will assist in maintaining the carbon layer 3 at a comparatively low temperature.

The durability of the negative electrode will be understood when it is remembered that the carbon deposit 6 is constantly maintained dur ing the flow of the current, whereby that portion of the carbon layer 3 which is exposed by the opening 5 in the copper coveringeis constantly protected from the heat of the arc, while the copper coating excludes the air and prevents combustion of the carbon layer, which, even if heated to redness, cannot be consumed, while at the same time the metal rod 2 keeps the carbon layer cool and acts as a conductor for the current, thus avoiding heating by resistance.

The negative electrode thus formed will last for an indefinite period and will eltect a great saving in the cost of carbons as Well as a very material economy in the labor of the trim- IDGIS.

What I claim is 1. In an arc lamp, a negative electrode consisting of a metallic bar or rod having alayer of carbon upon one end inclosed or covered by a thin metallic plating, substantially as described.

2. In an arc lamp, the combination, with a positive electrode or carbon of usual form, of a negative electrode composedof a bar or rod of suitable metal having one end entirely covered by a layer of carbon, which is in turn inclosed by a thin plating of copper, substantially as described.

In testimony whereof I have hereunto set my hand and aflixed my seal in presence of two subscribing Witnesses.

ALBERT C. SEIBOLD.

Witnesses:

CHRISTIAN G. Monrrz, HENRY HOYT. 

